Double finish drawing die



1952 J- H. PFEIFFER ETAL 2,616,127

DOUBLE FINISH DRAWING DIE Filed Sept. 21, 1950 40 v mh v N mo m 2 I Y lM; h 5% N 6| I 1 m a m 5 0 I E N N i 9; I m 4 Pl 0 LLI E q I M i n :25 8N i E w Q I 2 a) I 9 N INVENTOR. N DAVID A. BARRY JAMES H. PFEIFFER BY h-n m DES JARDINS, ROBINSON KEISER THEIR ATTORNEYS Patented Nov. 4, 1952DOUBLE FINISH DRAWING DIE James H. Pfeifler and David A. Barry, NewBrunswick, N. J assignors to Nixon Nitration Works, Nixon, N. 3., acorporation of New Jersey Application September 21, 1950, Serial No.185,933

16 Claims. 1

This invention relates to a double finish drawing die through whichplastic tubing is drawn subsequent to its extrusion for being finishedto accurate size, and it particularly pertains to a finish drawing dieprovided with a readily detachable bushing through which extrudedplastic tubing is drawn while submerged in a fluid.

Heretoiore, spaced apart plates, each recessed to form die openings,have been used for the finish die. The wall of the recess has beentransversely concaved to provide an annular groove surrounding each ofthe die openings for the tubing to be drawn therethrough. A hole leadingto the groove is formed in the plate through which water can becirculated against the outside wall of the tubing as it is drawn throughthe die opening. These plates are clamped to the end of a tank inposition to be submerged beneath the fluid level of a fluid containedwithin the tank. A plurality of these plates are detachably mounted toone of the tank walls which also has a die opening therein.Longitudinally spaced from these plates is another draw plate on the endof a casing projecting within the tank and recessed to admit waterwithin the casing to surround the tubing as it is drawn through thecasing and the die plates on the opposite ends thereof. A structuretypifying this prior art is shown in Slaughter Patent No. 2,383,520,issued August 28, 1945. This structure, however, does not lend itself tomaking tubing of varying sizes, but is adapted for tubing of only onesize. Even though some of the plates are detachably connected to thewall of the tank, that tank wall also has a die opening, and the casingand the opposite plate are integral therewith. This construction doesnot provide for the use of interchangeable dies. Moreover, the walls ofthe openings cannot be elongated lengthwise without using very thickplates or a series of them, and then the tubing in the die opening isnot exposed to the fluid.

Accordingly the principal object of our invention is to provide a finishdrawing die in which the drawing die element permits distribution of afluid upon the outside wall of the tubing while being drawn through saiddie element.

Another object of the invention is to provide a drawing die in which thedrawing die element is readily detachable.

Another object of the invention is to provide a drawing die which issimple in construction and efi'icient in operation.

Another object of the invention is to provide a drawing die in whichthere is more. efiective application of the fluid to the outside wall orr the drawn tubing.

Another object of theinvention is to provide a drawing die in which thedrawing die element is non-fixedly attached to its support.

Further objects, and objects relating to details of construction andeconomies of operation,'will readily appear from the detaileddescription to follow. In one instance I have accomplished the objectsof my invention by the device and means set forth in the followingspecification. My invention is clearly defined and pointed out in theappended claims. A structure constituting a preferred embodiment of myinvention is illustrated in the accompanying drawings forming a part ofthis specification, in which:

Fig. l is a side longitudinal sectional elevation of a drawing dieembodying our invention.

Fig. 2 is an end view of the right hand end of the finish die.

The invention generally described comprises a finish drawing die whichis adapted to be submerged in a tank of fluid, such as water, and isdisposed adjacent the discharge end of a conventional tube extrudingdevice. Air is ejected into the extruded tubing through means in thecore of the extruder to keep said extruded'tubing expanded until it isdrawn through the finish dieand cooled sufficiently to beself-sustaining. It is desired to cool the exterior surface of theextruded tubing immediately upon its emergence from the extruder so asto prevent shrinkage and warpage, and the finish die is provided with' ameans so disposed to insure a flow of cooling fluid to the top of thetubing and down both sides thereof.

The drawing die is a complete unit adapted to be clamped to the wall ofa water tank in position to receive the extruded tubing that isdischarged from the extruder and be submerged below the liquid level ofthe water contained I within the tank. The die unit is of substantiallength comprising a tubular casing having a bushing or sleeve slidablymounted in its opposite ends in spaced apart relation. The wall of thetubular casing is perforated to allow access of the water from the tankto each of the bushings and also to the space in the casing between thebushings. Accordingly, the exterior wall of the tubing is exposed to thefluid throughout'the entire length of the drawing die unit. Each of thebushings has constricted opposite ends to provide an intervening spacethat is connected to a fiuid supply hole in the unit through which fluidis permitted to surround the tubing between the restricted ends of thebushing. The bushings or sleeves are each held within a holder attachedto opposite ends of the casing. These holders have a bore conforming tothe exterior conformation of the bushings so that the bushings aresnugly fitted therein with an end abutting against a stepped portionformed on the core wall. The steps are" onthe discharge ends of thebushing. The bushings are detachably'connec'ted by being inserted in theholders on the feed side and may be held in place against the steps bythe tubing being drawn through the die unit. Bushings with difierentsize bores are interchangeable within the bushing holdersbymerelywithdrawing one and inserting another. Th'ey"do"not"require beingfixed to the holders-"astheyare held in place by the tubingbeingdrawnxthroughthe unit.

Referring specifically to the drawings, in which like numerals are usedto designate like parts,

'1num'eral'2 i'is a: tubing'that :is extruded from a plastic massthrough a conventional extruder de- "vi'c'e:foriormingitubing. :Air isinjected into the "tubing z asz it1isformedto keep "it inflatedandpreventcollapsing-of'the walls until drawn to -A' fini'sh die 3 'isprovided adjacent the disitself, and can'beused withxany tank. The tankdoesnotneed-to be of'any special construction.

Thefinish die'comprises a tubular casing! of "substantial-length havinga bushing mounting 5 in one end and another bushing mounting 6 in its'oppositeend. The two bushing mountings -5 '-and 6: are spaced apart toprovide an interveningchamberand-are fixed to the casing by welding.Bearing mounting 5 has an annular flange Icon its outer .end forabutting against .the endeofithe casing in which it is inserted forbeing secured in place. This mounting is recessedon its inner wall withan annular groove -8 to providea chamber surrounding a bushing or sleeve9 that is inserted therein to seat on the .-inner .wall portions 1 0.vannularlflange i I is formed near the outer end of the bushing.mounting -to..provide a thrust wabutmentiorone endof the bushing, thebushingbeing.adaptedtgsnuglyflt within the bore An inwardly extending ofthe bushing mounting and is inserted therein .in the end opposite vtothe flanged end. One or (more water holes .I 2 are formed radiallythrough .thebushing mountingand .the-endof the tubular casingileading tothe annular groove 8 between the bushing mounting and .the bushing.These holes .are preferably diametrically Opposed. 'There are also oneor more radial water holes i3 formed in thebushing between its oppositeends connecting the am1ular .groove 8 with annular groove [4 formedinthe interior wall of the bushing between resultant annular end flangesi5. These holes l3 are also preferably diametrically opposed.Accordingly water from the tank has access through the water holes tocontact with the exterior wall of the tubingas-it isbeing drawn throughthe bushing, and with the holes diametrically opposed the entiresurrounding wall of the tubing :is exposed to the ifluid.

v.f lhe other :bushing mounting: 6 zhas zarr annuthe front end of thebushing from the groove 2!].

Other passages 26 from the groove 20 are formed to be in registrationwith the radial passages 21 formed through the wall of a bushing 23which slidabl-y fits within the bushing mounting 5 to abut against astep 29 on its inner wall. This bushing ZBIhas'anintermediate annulargroove 3B 15 in'terior wall of the bushing.

formedbetweenresulting end flanges 35 on the Immediately beneath thebushing 28, there is a passage 35 leading to the front end face or thebushing mounting and in communication with the botsomewhat from the .endof the casing for having a plate 4| also attached to the end of thecasing between the end of this sleeve 40 and the flange 23 on thebushing mounting. 'The plate 4| pro- .vides means for attaching thedrawing die unit to the wall 1 of the tank by means of bolts to beprojected through .perforations 43 in the plate. Agasket 44 is insertedbetween the plate and the wall of the tank.

A slide closure is attached to the front of the plate 4! by means ofscrews 45 which projects through recesses 46 in the closure 44 to bescrewed to the plate 4|. These recesses 46 are vertically elongated topermit the closure 44 being adjusted vertically to regulate the volumeof flow of fluid through the passages 25. A series of passages 25 areprovided and so disposed that the flow of fluid therethrough will fallupon the top of the extruded tubing and down both of its sides tocontact and cool the entire outer circumference of the extruded tube.Holes 41 are formed through sleeve 60 and the end of the casing to forma passage from the annular groove 20 to the outside -of the casing.

Other holes 48 are formed'in the wall of the tubular casing between thebushing mountings so that there will be free entrance of watertherethrough to the intervening chamber within the casing forsurrounding the entire wall of the eX- truded tube which is being drawnthrough the die. The entire outer wall of the tubing through the entirelength of the drawing die unit is exposed to the fluid.

The bores of the bushings are slightly tapered with the first bushingthrough which the tube passes from the extruder having a taper or fromabout .418 to .460 whereas the taper of the second bushing is from about.460 to .402. The air within the extruded tube inflates and expands theouterwall of the tubing in contact with the bushings through which it isbeing drawn.

From the foregoing description it will be apparent that 'theextruded'tubing is immediately chilled or cooled by the fluid which is permittedto trickle .down upon the top of the tubing and flow' downiboth itsoppositesides. As the'tubing is then drawn through the first bushing, itis entirely surrounded by the fluid which is permitted to circulatethrough the bushing and lubricate the surfaces of the flanges which arein contact with the outer wall of the tube. The extruded tubing is alsosurrounded by the fluid as it passes through the tubular casing from thefirst to the second bushing where it is also surrounded by the fluid inbeing drawn therethrough in contact with the flanges on the interiorwall of the second bushing.

Both of the bushings are held within the bushing mountings by simplybeing inserted therein to abut against the steps, and either of thesebushings may be readily replaced with others having a different sizebore but of the same overall size to fit within the mounting. Thedrawing die is a complete unit in and of itself and can be fitted to anytank.

The tubing may be formed from any suitable plastic material, such ascellulose derivatives, particularly cellulose acetate and celluloseacetate butyrate, polymerized vinyl material, and other such resincompositions that are commonly extruded in continuous lengths.

We are aware that there may be various changes in details ofconstruction without departing from the spirit of our invention, and,therefore, we claim our invention broadly as 1ndicated by the appendedclaims.

Having thus described our invention what we claim as new and useful anddesire to secure by United States Letters Patent, is:

1. A finish die for drawing plastic tubing comprising a bushing havingan interior wall with an intermediate annular uncovered groove formedtherein, between tube finishing annular flanges against which the drawntube is adapted to be expanded and a support for the bushing, saidbushing being provided with a passage leading to the annular groove forapplying a cooling fluid to the exterior wall of the tubing being drawnthrough the die.

2. A finish die for drawing plastic tubing as set forth in claim 1 inwhich the bushing support is provided with a passage in communicationwith the radial passage in the bushing.

3. A finish die for drawing plastic tubing comprising a plurality ofspaced apart bushings, each having an interior wall with an intermediateanr nular groove formed therein, and a common support for the bushings,said common support and the bushings being provided with passages incommunication with the annular grooves in the bushings.

' 4. A finish die for drawing plastic tubing as set forth in claim 3 inwhich the common support for the bushings is a tubular casing having thebushings mounted in opposite ends thereof.

5. A finish die for drawing plastic tubing comprising a plurality ofspaced apart bushings, each of which has an interior wall provided withan intermediate annular groove, a mounting for each of thebush'ings, anda tubular casing to, which the bushing mountings are attached, saidcasing, bushing mountings, and the bushings being provided with passagesleading to the annular grooves in the bushings.

6. A finish die for drawing plastic tubing as set forth in claim 5having closure means on the feed side for distributing fluid from thedie upon the tubing as it is fed to said die.

7. A finish die for drawing plastic tubing as set forth in claim 6 inwhich the means for distributing the fluid upon the tubing is adjustablefor regulating the flo-w volume of said fluid.

8. A finish die for drawing plastic tubing comprising a tubular casing,a bushing mounting fitted to each of the opposite ends of the casing, abushing slidably fitted in each of the bushing mountings, and meansprovided in tubular casing, the bushing mountings, and the bushingsthrough which a fluid is circulated to surround the tubing as it isdrawn through the die.

9. A finish die for drawing plastic tubing as set forth in claim 8 inwhich each of the bushings is provided with an annular groove on itsinner wall for containing the circulating fluid.

10. A finish die for drawing plastic tubing as set forth in claim 9 inwhich closure means is also provided for distributing fluid from the diearound the outside wall of the tubing as it enters said die.

11. A finish die for drawing plastic tubing as set forth in claim 10 inwhich the closure means for distributing the fluid on the exterior wallof the tubing is adjustable for regulating the flow of the fluid.

12. A finish die for drawing plastic tubing as set forth in claim 11 inwhich the closure means for distributing the fluid comprises a pluralityof discharge openings with one passage on opposite sides of the verticalaxis.

13. A finish die for drawing plastic tubing comprising a tubular casing,a bushing mounting fitted to each of the opposite 'ends of the casingand spaced apart, a bushing slidably fitted within each of the bushingmountings and provided with an annular groove between annular endflanges, and passages formed in the bushing connecting the annulargroove therein with passages leading to the exterior of the casing.

14. A finish die as set forth in claim 13 in which the bushings areaxially slidable within the mounting and held therein by the tubingbeing drawn through the die.

15. A finish die for drawing plastic tubing comprising a casing in whicha supply of cooling fluid is adapted to, be contained and through whichthe tube is to be drawn, and a finish die bushing mounted in said casingin position to be submerged in the cooling fluid, said die bushing beingprovided with an annular groove between tube finishing annular flangesand said bushing having a passage leading to the annular groove forapplying a cooling fluid to the exterior wall of the tube drawn throughthe die.

16. A finish die as set forthin claim 15 in which the die bushing ismounted in opposite ends of the casing. 5

JAMES H. PFEIFFER.

DAVID A. BARRY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

